title: Ulipristal acetate prevents ovulation more effectively than levonorgestrel: analysis of pooled data from three randomized trials of emergency contraception regimens.
abstract: BACKGROUND
  The days just prior to ovulation are the most crucial for emergency contraception (EC) efficacy. Ulipristal acetate (UPA) and levonorgestrel's (LNG) capacity to inhibit follicular rupture have never been compared directly at this time of the cycle.
  
  
  METHODS
  Raw data from three pharmacodynamics studies with similar methodology were pooled to allow direct comparison of UPA, LNG and LNG + meloxicam's ability to prevent ovulation when administered orally in the advanced follicular phase, with a leading follicle of ≥ 18 mm.
  
  
  RESULTS
  Forty eight LNG-treated (1.5 mg) cycles, 31 LNG (1.5 mg) + meloxicam (15 mg), 34 UPA (30 mg) cycles and 50 placebo cycles were compared. Follicle rupture was delayed for at least 5 days in 14.6%, 38.7%, 58.8% and 4% of the LNG-, LNG + meloxicam-, UPA- and placebo-treated cycles, respectively. UPA was more effective than LNG and placebo in inhibiting follicular rupture (p = .0001), while LNG, when administered at this time of the cycle, was not different than placebo. The addition of meloxicam improved the efficacy of LNG in preventing follicular rupture (p = .0292 vs. LNG; p = .0001 vs. placebo; non-significant vs. UPA). UPA was effective in preventing rupture in the 5 days following treatment, even when administered at the time of the luteinizing hormone (LH) surge (UPA 79%, LNG 14% and placebo 10%). None of the treatments were effective when administered on the day of the LH peak. The median time from treatment to rupture was 6 days during the ulipristal cycles and 2 days in the placebo and LNG/LNG + meloxicam cycles (p = .0015).
  
  
  CONCLUSIONS
  Although no EC treatment is 100% effective in inhibiting follicular rupture when administered in the late follicular phase, UPA is the most effective treatment, delaying ovulation for at least 5 days in 59% of the cycles. LNG is not different from placebo in inhibiting follicular rupture at this advanced phase of the cycle. No treatment was effective in postponing rupture when administered on the day of LH peak.
authors.affiliation: PROFAMILIA, Santo Domingo, Dominican Republic. Electronic address: vbrache@gmail.com.
authors.forename: Vivian
authors.initials: V
authors.lastname: Brache
authors.forename: Leila
authors.initials: L
authors.lastname: Cochon
authors.forename: Maëva
authors.initials: M
authors.lastname: Deniaud
authors.forename: Horacio B
authors.initials: HB
authors.lastname: Croxatto
mesh_terms: D000293:Adolescent; D000328:Adult; D002677:Chile; D003282:Contraceptives, Postcoital, Hormonal / Q000494:pharmacology*; D003283:Contraceptives, Postcoital, Synthetic / Q000494:pharmacology*; D018592:Cross-Over Studies; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004293:Dominican Republic; D004311:Double-Blind Method; D004338:Drug Combinations; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D016912:Levonorgestrel / Q000494:pharmacology*; D034461:Luteinization / Q000187:drug effects; D007986:Luteinizing Hormone / Q000097:blood; D000077239:Meloxicam; D009649:Norpregnadienes / Q000494:pharmacology*; D006080:Ovarian Follicle / Q000187:drug effects*; D010060:Ovulation / Q000187:drug effects*; D013843:Thiazines / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D055815:Young Adult
chemical_list: D003282:Contraceptives, Postcoital, Hormonal; D003283:Contraceptives, Postcoital, Synthetic; D016861:Cyclooxygenase Inhibitors; D004338:Drug Combinations; D009649:Norpregnadienes; D013843:Thiazines; D013844:Thiazoles; D016912:Levonorgestrel; D007986:Luteinizing Hormone; D000077239:Meloxicam; C555622:ulipristal acetate
keywords: Emergency contraception; LH surge; Levonorgestrel; Ovulation inhibition; Ulipristal acetate